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Feb 28, 2012

How do you treat an uncomplicated urinary tract infection? What is your go to agent? There’s no best answer because much of it depends on your local resistance and susceptibility patterns. But one drug that causes some confusion is nitrofurantoin. For the most part, it’s a great first line agent for uncomplicated cystitis, but what about pyelonephritis? What about the elderly? There‘s a great paper from 2011 in the journal Clinical infectious disease called:

Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases

http://www.uphs.upenn.edu/bugdrug/antibiotic_manual/idsa-cystitispyelo-2010.pdf

Here's a brief summary of the paper

Cystitis-

1st choice Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days)

2nd choice Trimethoprim-sulfamethoxazole (160/800 mg [1 double- strength tablet] twice-daily for 3 days) if resistance is less than 20%

Quinolones are not the best first choice because of what's known as 'collateral damage'.  Here's what the guidelines have to say: Use of fluoroquinolones has been linked to infection with methicillin-resistant S. aureus and with increasing fluoroquinolone resistance in gram-negative bacilli, such as Pseudomonas aeruginosa. 

Bottom line: Quinolones certainly work, but may cause complications down the road. Granted, sometimes a quinolone is needed such as in cases of resistance, treatment failure, drug interaction or allergy.

Beta lactams can be used if none of the above are options, but have inferior efficacy and more adverse effects, compared with other UTI antimicrobials.

Amoxicillin, although still prescribed for some UTIs, especially in peds, is not a good choice for empiric management. 

Pyelonephritis:

1st choice Ciprofloxacin.

Oral TMP-sulfa and Beta Lactams are distant seconds

 Nitrofurantoin, although great for cystitis, is not recommended for pyelonephritis

Admitted patients: IV ceftriaxone, ciprofloxacin and aminoglycosides are all good choices.

A 2009 study from the Canadian Pharmacists Journal called :A retrospective review assessing the efficacy and safety of nitrofurantoin in renal impairment

http://www.cpjournal.ca/doi/pdf/10.3821/1913-701X-142.5.248

casts doubt on the dangers of nitrofurantoin, finding that it is just as effective in patients with renal insufficiency without an increase of adverse events.

Since there is conflicting data, I'd say don't use nitrofurantoin as your first line in elderly patients with deceased gfr or those with renal insufficiency in general. But if it's your only option because of resistance, med interactions or allergies, there is some (retrospective, limited) evidence to say its ok.